Shown in FIG. 1 is a typical rack 10 known to the inventors for electroplating articles such as to deposit a layer of chrome on a plastic automotive component. Rack 10 includes a plurality of part-gripping elements 12 for holding articles 14 during an electroplating process. Rack 10 is provided with an electrically insulative coating (e.g., a plastic coating) that covers an electrically conductive frame, so that generally all surfaces of the electrically conductive frame that are submerged in an electrolyte during an electroplating process are covered, such that the only electrically conductive components of the rack exposed to the electrolyte are typically the part-gripping elements 12, which in addition to holding articles 14 are electrically connected to articles 14 to conduct current from the articles, through the frame of rack 10 and to a rail 20 from which rack 10 is suspended by electrically conductive hooks 25.
During the electroplating process, metal ions are released into the electrolyte from an anode material that is in contact with the electrolyte and migrate toward and become deposited on exposed surfaces of the articles 14 that are being electroplated. A net movement or flux of metal ions from the anode to articles 14 (which are made cathodic) is driven by an electrical potential between the anode and articles 14.
In a conventional electroplating process using rack 10, articles 14 are held in a stationary position relative to rail 20, rack 10 and a container or vessel holding an electrolyte. In such processes, there is a tendency for plating deposits to be thicker at sharp edges and corners. These heavier deposits of plating material at the edges and corners of the articles being plated forms aesthetically undesirable, non-uniformly thick features. In order to reduce or eliminate this problem and provide more uniform coating thicknesses at sharp edges and/or corners, shielding, such as ledges 30, 32 are provided adjacent the sharp edges of articles that are to be electroplated such as the upper and lower edges of articles 14. The design of appropriate shielding for any particular article having a selected orientation on an electroplating rack is both an art and a science that often requires considerable intuition and/or trial and error. Accordingly, it would be desirable to develop an electroplating rack and process in which the difficulties associated with designing appropriate shielding to reduce non-uniform plating at sharp edges and corners of articles could be eliminated or at least significantly reduced. In addition, by eliminating or at least substantially reducing the need for shielding, the cost of making and repairing electroplating racks would be reduced. For example, it is not uncommon for an electrically insulative coating on an electroplating rack 10 to develop a hole or other imperfection that allows chrome or other plating material to deposit on the rack rather than only on articles 14. In such case, it is generally necessary to completely remove the defective electrically insulative coating from the electroplating rack and apply a new insulative coating. The difficulty and cost associated with this type of repair can be substantially reduced if the shielding, and hence the electrically insulative coating on the shielding, could be eliminated.